Cacheuta Mine, Cerro de Cacheuta, Sierra de Cacheuta, Cacheuta District, Luján de Cuyo department, Mendoza Province, Argentinai

Regional Level Types
Cacheuta Mine	Mine (Lost)
Cerro de Cacheuta	Mountain
Sierra de Cacheuta	Sierra
Cacheuta District	District
Luján de Cuyo department	Department
Mendoza Province	Province
Argentina	Country

Nowadays, the location of the Sierra de Cacheuta Se occurrence is not precisely known; it has never been recovered. It was discovered sometime between 1860–1862. In the earliest and most detailed description of the area, the following information was provided: The occurrence encompasses several small selenide veinlets ranging in thickness from 1 to 2 mm to a maximum of 4 cm. The main selenium minerals were clausthalite and copper selenides. Near the surface, the ore veins contained Ag contents of up to 21 wt %. At depth, the Ag content decreased rapidly down to almost zero at only 12 m depth — the reason the mining activity had been terminated.
Geographically, the occurrence was located on the right bank of the Rio de Mendoza, where it came from the Sierra de Cacheuta in the West. The mines were on the southern slope of the mountain range, a few leguas (miles) from the river. The slope was built up by andesitic to trachytic rocks, which had vesicular cavities locally filled with calcite or agate. The volcanic host rocks varied in texture from stratified to massive and were irregularly jointed. Stelzner examined the post-volcanic selenium veinlets in several small galleries, which were mined at different heights on the slope. On the surrounding dumps, he found only two little veinlet fragments, consisting mainly of granular ankerite and minor ore minerals. At the bottom of the mountain range, sandy, calcareous, or marly sediments occurred, with intercalations of bituminous shale and local asphalt enrichment. Brackebusch (1893) also mentioned bitumen (“Erdpech” in German) as a constituent of the Se veins. Ramdohr (1975) identified the following main ore minerals: klockmannite, clausthalite, eucairite, umangite, naumannite, accessory ferroselite, and two unspecified cobalt selenides. The sulphides were chalcopyrite and pyrite.